Two-stroke combustion engine



July 7, 1936. A. LESAGE TWO-STROKE COMBUSTION ENGINE Filed June 8, 1934 Fig. 1.

Fig. 3.

Inventor Patented July 7, 1936 UNITED STATES PATENT OFFICE 1.04.392

Alfred Lesage, Schweinfurt, Germany Application June 8, 1934, Serial No. 729,550 In Germany This invention relates to two-stroke combustion engines, and more particularly to that type thereof in which the distribution of the driving medium and the control of the exhaust of the.

burnt gases is operated through the piston cooperating with ports provided in the wall of the engine cylinder.

The standard two-stroke engines have the disadvantage that the burnt gases are not allowed to integrally leave the exhaust port but that there is always left a residue thereof which mixes with the fresh gases so as to result in a gas mixture less eflicient. The reason for the above-mentioned inconvenience consists in' that the fresh gases admitted are not able to scavenge all corners and points of the explosion chambers.

The object of the invention is to provide for a particular flow of the fresh gases intended for at the same time accomplishing the scavenging action in the engine cylinder, these gases being gradually deviated in their flowing direction. In this case there is an inversion of the flow in the direction of the cylinder axis but also a slight lateral deviation so that a helical motion is producedthrough the whole combustion chamber. This efiect is obtained by two parallel inlet .ports being arranged in a tangential direction with respect to the cylinder wall and a discharge port at approximately diametrically opposite points on the cylinder wallwhile the shape of the piston head is multiple grooved to assist the corresponding double deviation of the flow. This aim is further arrived at by a cupola-shaped cylinder head.

This and other objects of the invention will appear as the description thereof proceeds and reference may be had to the appended drawing which illustrates an embodiment of the novel disposition intended for producing the said scavenging process. In said drawing, which forms a part of this specification- Fig. 1 is a vertical sectional elevation of a cylinder and a side view of the piston;

Fig. 2 is a sectional view of thecylinder and a side view of the piston in a position turned through an angle of 90 degrees as compared with Fig. 1; I

Fig. 3 shows a vertical section of the piston on line AB of Fig. 2; and V Fig. 4 is a horizontal section of the cylinder on the line 0-1) of Fig. 2, the piston being shown in end view. As shown in Fig. 4, two parallel inlet or admission ducts Ill and Ill are disposed a tengential and slanting direction withreg to the June 16, 1933 l 2 Claims. (cl. EH5) cylinder head It in the cylinder wall, and opposite the said ducts there is arranged. also in a slanting direction with respect to the head l3, a radial exhaust duct ll. Thus the fed gases flow through the ducts Ill and Ill tangentially and 5 in an inclined direction upward towards a point on the cylinder wall'l2 located above the exhaust duct ll so that the two currents of gas are gradually deviated towards the vaulted cylinder head l3 and spirally from either side towards each other so as to push the exhaust gases towards the center of the cylinder and downward towards the exhaust port ll.

' In order that the streams of admission and exhaust gases are safely separated from one another in the neighbourhood of the inlet and out let openings and suitably guided within the cylinder, the piston head is, in accordance with the paths of flow of the fresh and exhaust gases, provided with transverse guide grooves, lateral curved rising grooves It being arranged for the fresh gas and disposed to communicate with the inlet ports l0 and Ill respectively while for the exhaust gases a sloping central groove It starts from points on the wall above and between the inlet parts and descends towards the exhaust port ll.

What I claim is- 1. A two-cycle internal combustion engine including a cylinder having a dome-shaped head, a pair of inlet ports inclined to the cylinder head and spaced apart circumferentially for directing the charge along parallel paths on opposite sides of a longitudinal central plane, and an exhaust port opposite to said inlet ports and in said plane, and a plstonadapted to uncover said ports at the lower end of its stroke and having its end surface presenting a pair of transversely extending lateral surface portions inclined upwardly from said inlet ports, and a transversely extending central surface portion on the piston between said first mentioned portions and inclined downwardly to said exhaust port, whereby, upon the uncovering of said ports, two streams are directed in looped helical paths from said inlet ports and converge to said exhaust port,'the axes of the helices being at. right angles to the axis of the 'cylinder and of opposite pitch.

2. In a two-stroke cycle combustion engine, the combination with a dome-headed cylinder having two parallel inclined inlet ports which are tangential with respect to the cylinder wall, and an outlet port located diametrically opposite and in a longitudinal plane central to the inlet ports, of a piston cooperating with said ports, 5

two lateral and substantially parallel guide grooves provided in the piston head corresponding'and joined to the inlet ports when at lower dead center position from which they rise to the opposite cylinder wall, and a central inversely sloping groove .formed between the lateral grooves, said central groove sloping down to the v outlet port, the scavenging twin stream entering through the inlet ports being guided by the lateral grooves to the opposite cylinder wall, deflected towards the dome-shaped head and reversed downward at the opposite side, whereby the waste gases are moved downwards and in the central 5 groove to the outlet port.

' ALFRED LESAGE. 

